What reason to put for not registering my child's birth?

Hello all, this is my first post so please do excuse me.  This is a great site with much information so i hope someone will be able to help me.

I am South African about to receive indefinite leave to remain in the UK and at a later stage my British passport but will also retain my South African citizenship as wish to return next year to SA.

I have been married to my wife for 5 years now, she is Czech and so holds a European passport.

Our daughter now 14 months old holds a British passport as my wife is excising her treaty right to live in the UK and has been for some 10 years.

We want to get my daughter a South African passport and having only done some homework on it would seem we have been bad parents for not registering her birth with in 30 days as requested.

We now have to give a reason why on the form and am not too sure what to put apart from ignorance and the fact that if you dont go looking for the information no one told us this needs doing.

Would that be a good enough reason or do i need to make something up?

It would not be too hard to come up with something as my Indefinite leave to remain application has gone of for some 14 months now and so i have not had my passport which i think they require a copy of. 

I don't want to get in the bad books but this would seem a stupid rule of no significant use or very difficult to enforce if o one knows you have to register your child in a certain time frame.

Your advise is much appreciated.